Don’t quit too early and regret it when shooting star trails.
When you’re trying to decide how long to shoot star trails, which is maybe the second-most asked question we get, the answer has always been: “As long as you can stand it!” However, I want to expand on that statement a little more with some real-world examples.
You should have a much better idea of what to expect from your star trails by the end of this article, and you should be able to decide how long your imaging sessions really need to be to get the results you want!
Things to think about
First thing — throw out everything you learned about exposing for perfect stars with the rule of 500 (which is meant to be broken anyway). Shoot to the 30-second limit of your camera’s exposure timer. Luckily, that also makes it easy to do the math!
You also need to familiarize yourself with your sky. Are you wanting to shoot circumpolar trails (those cool concentric circles)? Then you need to know where the celestial poles are for your location on the planet. North or south and how high? Depends on your latitude.
Or, do you want long, sweeping, slightly arcing or nearly straight lines, which is what happens at 90 degrees away from the poles in the east and west? And, how long do you want your star trail lines to be? Short, long, or mega-long?
I’m an engineer by day, and one thing I’ve learned over the years is when someone asks you for an estimate, take your first guess, double it, and add 20%. This is a pretty good procedure to follow when trying to decide how long your star trail shoots should be.
So, is there a magic number of time for the ultimate star trail image? Yes…and no, it depends. The general rule of thumb we go by is never shorter than 2 hours at the absolute minimum, and always as long as we can stand it.
However, rules, as I’ve said before, are meant to be broken in astrophotography. So I’ve prepared some examples for you to help determine how long you need to plan your star trails shoots for to get the result you want!
Some real-world star trail length examples
These real-world examples, shot in desert-dark skies by Tanja Schmitz, are set alongside simulations of the time and calculations of how many degrees in the sky the stars will move, courtesy of the PhotoPills app.
You’ll be able to see below how the amount of time you shoot star trails can have a massive effect on what the final image looks like!
Example: 1 hour
Images: 120 x 30 seconds, Motion: ~15° rotation
Example: 1.5 hours
Images: 180 x 30 seconds, Motion: ~22° rotation
Example: 2 hours
Images: 240 x 30 seconds, Motion: ~30° rotation
Example: 3.5 hours
Images: 420 x 30 seconds, Motion: ~53° rotation
Very informative, thank you.
Thanks for the info. I’ll have to get an electronic shutter release for my Nikon D3200, won’t I?
Our pleasure! Yes, you would need a shutter release for the D3200.
I just came back from my first attempt. Read all I could find here prior to heading out. Hoped for at least 1.5 hrs, got 40 minutes instead (I wasn’t driving). I came home, downloaded DSS and began to read how to use it. I didn’t know I was supposed to have darks or bios files, so I only have the picture or “Lights” to work with. I followed a tutorial on You Tube by Bob Salazar and my final image was pure white, nothing there.
I would be most grateful to hear from someone where to go to learn how to process my meager 40 minutes of shooting. A video, a good read. The help manual for DSS is just making my brain ache. I do better with videos but haven’t found one that is specific to star trails. Thanks for your help!
I’d highly recommend using StarStax (http://www.markus-enzweiler.de/software/software.html) to create your star trails, not DSS. It’s VERY easy to use! Also, you do not need darks or bias for star trails. It’s OK to use, but they are not at all required.
I gave up after 40 minutes last night, was on 20s shutter and repeat after every 40 seconds, I am in Iceland and thought wouldnt a star trail look great against the Northern lights ! I used no filters just my basic camera and trusty tripod, unfortunately -20 temperatures beat me. I used photoshop,
Files-scripts-load stack, browse to the folder, once all the pictures are loaded, change blend mode to lighten and voila a pretty short star trail ! But I did capture it along with some northern lights so gonna call that a win.
I assume you would shoot these images in jpeg?as raw files would be to large to process?
No, I recommend to always — ALWAYS — shoot raw! You edit them in raw in post, and then export to JPEG to stack into star trails.
Thanks Cory,i always shoot raw files so will continue to do so next time i’m out for star photos,cheers.
hello sir, awesome info
i saw another kind of taking pics for star trails
someone put his camera on bulb mode and shot for 3 hours none stop !
no closing and opening of diafragma he took all in raw
1 shot 3 hours instead of 100 shot with 30 secs
what do you think?? would it work with this kind of photographing??!!
sorry for my bad english
Yes, that is the “old” way to do it (in my opinion!). It works, but it is dangerous and unnecessary, especially with today’s cameras and post-processing software!
Hi there, I tried and when I put the photos into photoshop the final image has gaps between each trail, loads of them so each trail is not smooth but a dotted line, any help? I used a remote shutter but don’t have an intervalometer or anything and I took 30 second exposures, thanks
With star trails, you cannot have ANY time gap in between exposures, otherwise there will be gaps between stars in your shots. When you used the remote shutter, was there any delay from the time the shutter closed until it reopened again? That would likely be the cause.
Good luck and clear skies!
It is very difficult to not have gaps between frames because of shutter delay or card writing delay.
You could use a freeware piece of software called StarStax: http://www.markus-enzweiler.de/StarStaX/StarStaX.html#download
This can join all your images, masking small gaps/intervals and make the trails appear complete.
Also, check that you have long exposure noise reduction turned OFF, otherwise the camera will attempt to take a “dark” exposure of the same length after each exposure.
This happens if you had ‘Long Exposure Noise Reduction’ (LENR) turned ON. All (?) digital camera make a ‘blank’ exposure of equal length (30 sec. say) in order to deduct any erroneous pixels or artefacts from the image you actually took.
For example, my ageing Sony a900 has over a hundred false ‘stars’ on a 30 sec. exposure but they all disappear completely when LENR is turned ON. It also works perfectly for 30 minute exposures. I have not tried any longer because you eventually run into battery capacity issues with very long exposures as the camera needs to operate for twice as long with LENR ON. A film camera doesn’t have this problem. A Hasselblad SWC/M would be superb. Scanning in the 6×6 negative should give a better image than ANY DSLR. If only I could afford it ;(
is there a shutter release remote for a mirrorless camera with only micro usb port
i have a sony alpha 3500 asp-c 20.1 megapixels